The automotive industry is under regulatory pressure to reduce average fuel consumption and improve the crashworthiness of vehicles. To improve fuel consumption lighter and thinner materials are being used. Unfortunately, this reduces the structural integrity of parts of an automobile. To compensate automobile producers place structural reinforcing members into hollow structural members, such as A and B pillars of automobiles. Structural reinforcing members and their use in automobiles are described in Thum U.S. Pat. No. 5,194,199; Keller U.S. Pat. No. 6,146,565; Wycech U.S. Pat. No. 6,165,588; Hopton et al. U.S. Pat. No. 6,199,940; Barz U.S. Pat. No. 6,131,897 and Sheldon et. al, U.S. patent application 2002/0160130, all incorporated herein by reference. These structural reinforcing articles generally comprise some structural part, which gives the reinforcing articles shape and strength, which structural part is based on a light weight metal or a rigid plastic. The structural part is coated with an expandable composition, which expands when heated to a certain temperature. Typically the expandable composition expands to contact the inner walls of the structural member being supported. Upon expansion, the expandable composition functions to hold the structural reinforcing member in place permanently by adhering to the inner wall of the structural member or by friction because the expanded composition is wedged tightly in position. The expanded composition also helps transfer a load from sheet metal to inner reinforcement to sheet metal.
The expandable composition is applied to the structural part of the structural reinforcing member by conventional means known in the art, such as hand applied sheets of epoxy, compression molding, resin transfer molding and injection molding. Some of the expandable materials exhibit adhesive properties at elevated temperatures. This is desirable for affixing the expandable composition to the structural part of the structural reinforcing member. The adhesive properties can cause problems in manufacturing of the structural reinforcing member because it can be difficult to remove the structural reinforcing member with the expandable materials deposited thereon from the mold. In order to pump the expandable material and apply it, it is necessary to heat the expandable material and the mold to facilitate application. Thereafter to prevent, or reduce adhesion to the mold, the mold is cooled prior to opening the mold. Even when cooled some of the expandable materials will still adhere to the mold, forcing an operator to manually remove some of the expandable material. Heating the mold to application temperature and then cooling before attempting to remove the coated structural reinforcing member results in long processes, up to an hour per part per mold. In high volume parts manufacture this results in the need for large amount of capital to keep up with the demand for the part. In addition to the long cycle times there are post process steps that may need to take place to make a tack free part including but not limited to dusting of the surface of the expandable material with a material which renders the surface tack free such as glass balloons.
What is needed is a part that can be manufactured in an efficient manner with low part residence times in molds and little or no post molding processing steps. What is also needed is a process, which can produce expandable material coated articles, such as structural reinforcing members, in a cost efficient manner maximizing the productivity of tools used to manufacture the parts.